Origin of cadmium-induced reactive oxygen species production: mitochondrial electron transfer versus plasma membrane NADPH oxidase


Author for correspondence:
Anja Krieger-Liszkay
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  • • Cadmium (Cd2+) is an environmental pollutant that causes increased reactive oxygen species (ROS) production. To determine the site of ROS production, the effect of Cd2+ on ROS production was studied in isolated soybean (Glycine max) plasma membranes, potato (Solanum tuberosum) tuber mitochondria and roots of intact seedlings of soybean or cucumber (Cucumis sativus).
  • • The effects of Cd2+ on the kinetics of superoxide (inline image), hydrogen peroxide (H2O2) and hydroxyl radical (OH) generation were followed using absorption, fluorescence and spin-trapping electron paramagnetic resonance spectroscopy.
  • • In isolated plasma membranes, Cd2+ inhibited inline image production. This inhibition was reversed by calcium (Ca2+) and magnesium (Mg2+). In isolated mitochondria, Cd2+ increased inline image and H2O2 production. In intact roots, Cd2+ stimulated H2O2 production whereas it inhibited inline image and OH production in a Ca2+-reversible manner.
  • • Cd2+ can be used to distinguish between ROS originating from mitochondria and from the plasma membrane. This is achieved by measuring different ROS individually. The immediate (≤ 1 h) consequence of exposure to Cd2+ in vivo is stimulation of ROS production in the mitochondrial electron transfer chain and inhibition of NADPH oxidase activity in the plasma membrane.